1. Field of the Invention
This invention relates generally to gas turbine engines wherein motive fluid is generated by combustion of finely powdered coal and, more particularly, to an improvement in linear pocket feeders for metering the powdered coal to the combustor of the engine.
2. Description of the Prior Art
U.S. Pat. No. 4,342,428, issued on Aug. 3, 1982 to Thomas P. Kosek and assigned to the assignee of this invention, disclosed a powdered coal metering system for an automotive gas turbine engine wherein a linear pocket feeder transports the powdered coal from a reservoir at atmospheric pressure to a supply duct leading to the engine's combustor at a pressure exceeding the engine's compressor discharge pressure. In Kosek's linear pocket feeder, an endless chain with spherical or disc-like flights fixed thereon is pulled through a tube extending between the reservoir and a port to the supply duct. The flights seal against the inside diameter of the tube to isolate the high pressure duct from the reservoir while the powder is carried between the flights. While this and similar linear pocket systems function as intended, the relatively large quantities of powder carried between the flights tend to eject from the feeder into the supply duct en masse, causing a noticeable pulse in the flame in the combustor. A linear pocket feeder according to this invention represents an improvement over these known structures through material reduction in flame pulsation.